Reduction in complexity is at least conceivable, I'll grant. For example if someone invented a zero point energy generator with the cost and form factor of an AA battery, much of the complexity associated with the energy industry could disappear.
But this seems highly unlikely. All the current evidence suggests the contrary: the breakthroughs that will be necessary and possible in the coming century will be precisely those of complex systems (in both senses of the term).
Human level AGI in the near future is indeed neither necessary nor possible. But there is a vast gap between that and what we have today, and we will, yes, need to fill some of that gap. Perhaps a key breakthrough would have come from a young researcher who would have re-implemented Eurisko and from the experiment acquired a critical jump in understanding - and who has now quietly left, thinking Eurisko might blow up the world, to reconsider that job offer from Electronic Arts.
I do disagree that AGI research is a fast danger. I will grant you that there is a sense in which the dangers I am worried about are slow ones - barring unlikely events like a large asteroid impact (which is likely only over longer time scales), I'm confident humanity will still exist 100 years from now.
But our window of opportunity may not. Consider that civilizations are mortal, for reasons unrelated to this conversation. Consider that environments conducive to scientific progress are even considerably rarer and more transient than civilization itself. Consider also that the environment in which our civilization arose is gone, and is not coming back. (For the simplest example, while fossil fuels still exist, the easily accessible deposits thereof, so important for bootstrapping, are largely gone.) I think it quite possible that the 21st-century may be the last hard step in the Great Filter, that by the year 2100 the ultimate fate of humanity may in fact have been decided, even if nobody on that date yet knows it. I cannot of course be certain of this, but I think it likely enough that we cannot afford to risk wasting this window of opportunity.
One problem with this argument is how conjunctive it is: "(A) Progress crucially depends on breakthroughs in complexity management and (B) strong recursive self-improvement is impossible and (C) near-future human level AGI is neither dangerous nor possible but (D) someone working on it is crucial for said complexity management breakthroughs and (E) they're dissuaded by friendliness concerns and (F) our scientific window of opportunity is small."
My back-of-the-envelope, generous probabilities:
A. 0.5, this is a pretty strong requirement.
B. 0.9, for...
In the early 1980s Douglas Lenat wrote EURISKO, a program Eliezer called "[maybe] the most sophisticated self-improving AI ever built". The program reportedly had some high-profile successes in various domains, like becoming world champion at a certain wargame or designing good integrated circuits.
Despite requests Lenat never released the source code. You can download an introductory paper: "Why AM and EURISKO appear to work" [PDF]. Honestly, reading it leaves a programmer still mystified about the internal workings of the AI: for example, what does the main loop look like? Researchers supposedly answered such questions in a more detailed publication, "EURISKO: A program that learns new heuristics and domain concepts." Artificial Intelligence (21): pp. 61-98. I couldn't find that paper available for download anywhere, and being in Russia I found it quite tricky to get a paper version. Maybe you Americans will have better luck with your local library? And to the best of my knowledge no one ever succeeded in (or even seriously tried) confirming Lenat's EURISKO results.
Today in 2009 this state of affairs looks laughable. A 30-year-old pivotal breakthrough in a large and important field... that never even got reproduced. What if it was a gigantic case of Clever Hans? How do you know? You're supposed to be a scientist, little one.
So my proposal to the LessWrong community: let's reimplement EURISKO!
We have some competent programmers here, don't we? We have open source tools and languages that weren't around in 1980. We can build an open source implementation available for all to play. In my book this counts as solid progress in the AI field.
Hell, I'd do it on my own if I had the goddamn paper.
Update: RichardKennaway has put Lenat's detailed papers up online, see the comments.